import { useForm } from "react-hook-form";
import { z } from "zod";
import { zodResolver } from "@hookform/resolvers/zod";
import { useState, useRef, useEffect } from "react";
import { useNavigate } from "react-router-dom";
import showToast from "../../services/toastService";
import { AuthWrapper } from "./AuthWrapper";
import { OTP_EXPIRY_SECONDS } from "../../utils/constants";
import AuthRepository from "../../repositories/AuthRepository";

const otpSchema = z.object({
  otp1: z.string().min(1, "Required"),
  otp2: z.string().min(1, "Required"),
  otp3: z.string().min(1, "Required"),
  otp4: z.string().min(1, "Required"),
});

const LoginWithOtp = () => {
  const navigate = useNavigate();

  const [loading, setLoading] = useState(false);
  const [timeLeft, setTimeLeft] = useState(0);


  const inputRefs = useRef([]);

  const {
    register,
    handleSubmit,
    formState: { errors, isSubmitted },
    getValues,
    setValue,
    trigger,
  } = useForm({
    resolver: zodResolver(otpSchema),
  });

  const onSubmit = async (data) => {
    const finalOtp = data.otp1 + data.otp2 + data.otp3 + data.otp4;
    const username = localStorage.getItem("otpUsername");
    setLoading(true);

    try {
      let requestedData = {
        email: username,
        otp: finalOtp
      }
      const response = await AuthRepository.verifyOTP(requestedData)

      localStorage.setItem("jwtToken", response.data.token);
      localStorage.setItem("refreshToken", response.data.refreshToken);
      setLoading(false);
      localStorage.removeItem("otpUsername");
      localStorage.removeItem("otpSentTime");
      navigate("/");

    } catch (err) {
      showToast("Invalid or expired OTP.", "error");

      setLoading(false);
    }
  };
  const formatTime = (seconds) => {
    const min = Math.floor(seconds / 60).toString().padStart(2, "0");
    const sec = (seconds % 60).toString().padStart(2, "0");
    return `${min}:${sec}`;
  };

  // Time Logic for OTP expiry
  useEffect(() => {
    const otpSentTime = localStorage.getItem("otpSentTime");
    const now = Date.now();

    if (otpSentTime) {
      const elapsed = Math.floor((now - Number(otpSentTime)) / 1000); //in seconds
      const remaining = Math.max(OTP_EXPIRY_SECONDS - elapsed, 0); //prevent negatives
      setTimeLeft(remaining);
    }
  }, []);


  useEffect(() => {
    if (timeLeft <= 0) return;

    const timer = setInterval(() => {
      setTimeLeft((prev) => {
        if (prev <= 1) {
          clearInterval(timer);
          localStorage.removeItem("otpSentTime");
          localStorage.removeItem("otpUsername");
          return 0;
        }
        return prev - 1;
      });
    }, 1000);

    return () => clearInterval(timer);
  }, [timeLeft]);

  // Handle Paste Event
  const handlePaste = (e) => {
    e.preventDefault();

    const pastedData = e.clipboardData.getData("text/plain").trim();
    if (pastedData.match(/^\d{4}$/)) {
      for (let i = 0; i < pastedData.length; i++) {
        setValue(`otp${i + 1}`, pastedData[i], { shouldValidate: true });

        if (inputRefs.current[i + 1]) {
          inputRefs.current[i + 1].focus();
        }
      }
      trigger(["otp1", "otp2", "otp3", "otp4"]);
    } else {
      showToast("Invalid OTP format pasted. Please enter 4 digits")

      for (let i = 0; i < 4; i++) {
        setValue(`otp${i + 1}`, "")

      }
    }
  }


  return (
    // <AuthWrapper>
   <div className="col-12 col-lg-5 col-xl-4 d-flex align-items-center justify-content-center p-4 p-sm-5 bg-gray-60 h-100">
  <div className="block p-4 p-sm-5 bg-gray-60">
        <h4>Verify Your OTP</h4>
        <p className="mb-4">Please enter the 4-digit code sent to your email.</p>

        <form onSubmit={handleSubmit(onSubmit)}>
          <div className="d-flex justify-content-center gap-6 mb-3">
            {[1, 2, 3, 4].map((num, idx) => {
              const { ref, onChange, ...rest } = register(`otp${num}`);

              return (
                <input
                  key={num}
                  type="text"
                  maxLength={1}
                  className={`form-control text-center ${errors[`otp${num}`] ? "is-invalid" : ""
                    }`}
                  ref={(el) => {
                    inputRefs.current[idx] = el;
                    ref(el);
                  }}
                  onChange={(e) => {
                    const val = e.target.value;
                    onChange(e);
                    if (/^\d$/.test(val) && idx < 3) {
                      inputRefs.current[idx + 1]?.focus();

                    } else if (val === "" && idx > 0) {
                      inputRefs.current[idx - 1]?.focus();
                    }
                  }}
                  onKeyDown={(e) => {
                    if (
                      e.key === "Backspace" &&
                      !getValues()[`otp${num}`] &&
                      idx > 0
                    ) {
                      inputRefs.current[idx - 1]?.focus();
                    }
                  }}

                  onPaste={idx === 0 ? handlePaste : undefined}
                  style={{ width: "40px", height: "40px", fontSize: "15px" }}
                  {...rest}
                />
              );
            })}
          </div>

          {isSubmitted && Object.values(errors).some((e) => e?.message) && (
            <div
              className="text-danger text-center mb-3"
              style={{ fontSize: "12px" }}
            >
              Please fill all four digits.
            </div>
          )}

          <button
            type="submit"
            className="btn btn-primary d-grid w-100"
            disabled={loading}
          >
            {loading ? "Verifying..." : "Verify OTP"}
          </button>

          {timeLeft > 0 ? (
            <p
              className="text-center text-muted mt-2"
              style={{ fontSize: "14px" }}
            >
              This OTP will expire in <strong>{formatTime(timeLeft)}</strong>
            </p>
          ) : (
            <div>
              <p
                className="text-center text-danger mt-2 text small-text m-0"

              >
                OTP has expired. Please request a new one.
              </p>
              <a className="text-primary cursor-pointer" onClick={() => navigate('/auth/login')}>Try Again</a>
            </div>

          )}
        </form>
        </div>
      </div>
    // </AuthWrapper>
  );
};

export default LoginWithOtp;